Hibernate对数据库的查询

本文介绍了Hibernate对数据库的查询的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我对hibernate对数据库执行的查询数量有问题。 这是我做查询日志（使用Mysql 5.1）到数据库时做一个简单的选择：

111125 7:18 ：30 27查询SET autocommit = 0 27查询SELECT @@ session.tx_isolation 27查询选择this_.id为id34_0_，this_.media_id为media3_34_0_，this_.message为message34_0_，this_ .user_id as user4_34_0_ from notifications this_ 27查询回滚 27查询SET autocommit = 1

我已经阅读了很多关于将autocommit设置为0，然后设置为1.我知道连接的默认值为1，并且不能更改此行为。你可以运行SET autocommit = 0，但结果是一样的。

有没有反对，以避免任何这些查询？我不知道为什么SELECT @@ session.tx_isolation正在发生和回滚。当我使用一个事务，我得到一个提交，然后回滚。

我的conf： Spring 2.5.6，Hibernate 3.6.0，Mysql 5.1

datasoure.xml：

code>< bean id =dataSourcedestroy-method =close class =org.apachemons.dbcp.BasicDataSource> < property name =driverClassNamevalue =$ {jdbc.driverClassName}/> < property name =urlvalue =$ {jdbc.url}/> < property name =usernamevalue =$ {jdbc.username}/> < property name =passwordvalue =$ {jdbc.password}/> < property name =initialSizevalue =3/> < property name =maxActivevalue =20/> < property name =minIdlevalue =3/> < attribute name =poolPreparedStatementsvalue =false/> < property name =defaultAutoCommitvalue =false/> < property name =defaultTransactionIsolationvalue =4/> < / bean>

交易经理定义：

< bean id =transactionManager class =org.springframework.orm.hibernate3.HibernateTransactionManager> < property name =sessionFactoryref =sessionFactory/> < / bean>

UPDATE ：通过设置新属性来管理回滚p>

< property name =defaultReadOnlyvalue =true/>

但现在的问题是你不能进行修改事务注释readOnly = false）到db给出一个SQLException。 此属性将只读连接设置为true。 我猜想没有办法用HibernateTemplate做这个。

我使用aspectj事务内部编织。

< aop：aspectj-autoproxy proxy-target-class =true/>

解决方案

您需要为应用程序配置事务。有关事务管理，请参见 Spring 2.5.x文档。

编辑12/3/11：即使对于只做选择的方法，您仍然必须创建一个只读事务，以便删除您在职位。只需写@Transactional（readOnly = true），你应该很好去。

编辑12/20/11：你还需要确保事务配置正确。您发布的配置可能会丢失< tx：注释驱动的/>注释。请参阅 Spring文档的第10.5.1节。

I'm having a problem with the amount of queries done by hibernate to the database. Here's my query log (using Mysql 5.1) to the database when doing a simple select:

111125 7:18:30 27 Query SET autocommit=0 27 Query SELECT @@session.tx_isolation 27 Query select this_.id as id34_0_, this_.media_id as media3_34_0_, this_.message as message34_0_, this_.user_id as user4_34_0_ from notifications this_ 27 Query rollback 27 Query SET autocommit=1

I've read a lot about setting autocommit to 0 and then to 1. I know that the default for a connection is 1 and this behaviour cannot be changed. You can run SET autocommit = 0 but the result is the same.

Is there anyway to avoid any of those queries? I don't know why the SELECT @@session.tx_isolation is happening and the rollback. When I use a transaction I get a commit and then a rollback. Not sure why a rollback is always cabled.

Thanks a lot!

My conf: Spring 2.5.6, Hibernate 3.6.0, Mysql 5.1

datasoure.xml:

<bean id="dataSource" destroy-method="close" class="org.apachemons.dbcp.BasicDataSource"> <property name="driverClassName" value="${jdbc.driverClassName}" /> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.username}" /> <property name="password" value="${jdbc.password}" /> <property name="initialSize" value="3" /> <property name="maxActive" value="20" /> <property name="minIdle" value="3" /> <property name="poolPreparedStatements" value="false" /> <property name="defaultAutoCommit" value="false" /> <property name="defaultTransactionIsolation" value="4" /> </bean>

Transaction manager definition:

<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory" ref="sessionFactory" /> </bean>

UPDATE: Managed to take out the rollback by setting new property

<property name="defaultReadOnly" value="true" />

But the problem now is that you can't make a modification (no matter if I set on the transactional annotation readOnly=false) to the db giving a SQLException. This property sets the connection readonly to true. I'm guessing there's no way to do this with HibernateTemplate.

I use aspectj transaction for inner code weaving.

<aop:aspectj-autoproxy proxy-target-class="true" />

解决方案

You need to configure transactions for your application. See the Spring 2.5.x documentation on transaction management.

Edit 12/3/11: Even for methods that only do selects, you still have to create a read only transaction in order to remove the extra queries you mentioned in your post. Just write @Transactional(readOnly=true) and you should be good to go.

Edit 12/20/11: You also need make sure transactions are configured correctly. It looks like the configuration you posted may be missing < tx:annotation-driven /> annotation. See section 10.5.1 of the Spring documentation.